Pad over active circuit system and method with meshed support structure

ABSTRACT

An integrated circuit and method of fabricating the same are provided. Included are an active circuit, and a metal layer disposed, at least partially, above the active circuit. Further provided is a bond pad disposed, at least partially, above the metal layer. To prevent damage incurred during a bonding process, the aforementioned metal layer is meshed.

RELATED APPLICATION(S)

The present application is a divisional of an application filed Jul. 31,2003 under application Ser. No. 10/633,004, which is incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to semiconductor integrated circuits, andmore particularly to integrated circuits with increased circuit densityand reduced size.

BACKGROUND OF THE INVENTION

Prior Art FIG. 1 illustrates an integrated circuit 100 constructed withbond pads around a periphery thereof, in accordance with the prior art.As shown, the integrated circuit 100 includes a semiconductor platform101. Incorporated on the semiconductor platform 101 are acentrally-situated core 102 and a peripheral input/output (I/O) bus 104,which together define an “active circuit” of the integrated circuit 100.The I/O bus 104 is positioned around a periphery of thecentrally-situated core 102.

Further included is a plurality of bond pads 106 which are disposedabout the outer periphery of the I/O bus 104. As can be seen, thepositioning of the bond pads 106 about the outer periphery of the I/Obus 104 requires that the overall size of the semiconductor platform 101be augmented.

To further illustrate this, Prior Art FIG. 2 includes a cross-sectionalview of the integrated circuit 100 of FIG. 1 taken along line 2-2.Similar to FIG. 1, the semiconductor platform 101 is shown to includethe centrally-situated core 102 and I/O bus 104, which together definethe “active circuit” of the integrated circuit 100 for processingelectrical signals. Further shown are the bond pads 106 which requirethat the overall size of the semiconductor platform 101 be augmented.

FIG. 2 further illustrates underlying metal layers 206 that areinterconnected by way of vias 208 for facilitating electriccommunication therebetween. As shown, the underlying metal layers 206take-on a stacked configuration for allowing various unillustratedinterconnections with the active circuit of the integrated circuit 100.Such underlying metal layers 206 are further coupled to the bond pads106. Also included is a passivation layer 210 for protection purposes.

Trends toward increased circuit density and complexity in modernintegrated circuit design have resulted in a desire for significantincreases in both: 1) the number of input/output and power/ground pinsper integrated circuit and, 2) the number of bond pads in order toconnect to the package. To conserve active device area, it is desirableto reduce the bond pad pitch. However, smaller bond pads are more easilydamaged by the large mechanical stresses inherent in the bondingprocess.

Generally, design rules have not allowed bonding pads over active areas,where they would be susceptible to damage from the large mechanicalstresses of bonding. There is thus a continuing need to devisestructures and layouts that satisfy the high-density requirements ofadvanced integrated circuit design and that would resist the highmechanical stresses of bonding.

DISCLOSURE OF THE INVENTION

An integrated circuit and method of fabricating the same are provided.Included are an active circuit, and a metal layer disposed, at leastpartially, above the active circuit. Further provided is a bond paddisposed, at least partially, above the metal layer. To prevent damageincurred during a bonding process, the aforementioned metal layer ismeshed.

The active circuit may include an input/output (I/O) bus. Still yet, theactive circuit may include a plurality of transistors. By virtue ofproviding an “interconnect” between a plurality of underlying metallayers and the bond pad, the meshed metal layer may include aninterconnect metal layer.

In one embodiment, the metal layer may be meshed by including aplurality of openings formed therein. Still yet, the openings may becompletely enclosed around a periphery thereof. Also, the openings mayhave a substantially square configuration.

In such embodiment, the openings may define a plurality of substantiallylinear first portions and a plurality of substantially linear secondportions which intersect, to define a matrix of openings. Thus, aplurality interconnect vias may be formed in rows along a length of atleast the first portions of the metal layer, in order to provideelectric communication between the metal layer and the bond pad.

In one version of the present embodiment, the interconnect vias mayinclude one single row for each of the first portions. In anotherrelated version of the present embodiment, the interconnect vias mayinclude at least two spaced rows for each of the first portions.Optionally, a width of the first portions of the metal layer may beenlarged to accommodate the at least two spaced rows for each of thefirst portions.

In use, the openings of each of the aforementioned embodiments may beadapted for not only preventing damage incurred during a bondingprocess, but also facilitating an interlock between the metal layer andan inter-metal dielectric layer disposed between the metal layer and thebond pad. This thus strengthens the integrated circuit.

As an option, the inter-metal dielectric layer may be constructed from amaterial selected from the group consisting of a low-K dielectricmaterial and a fluorinated silica glass (FSG) material.

A related method for fabricating an integrated circuit is furtherprovided. Initially, an active circuit is constructed on a semiconductorplatform. Moreover, a metal layer is deposited, at least partially,above the active circuit. Next, a dielectric layer is deposited, atleast partially, above the interconnect metal layer. A bond pad issubsequently formed, at least partially, above the metal layer.Thereafter, a passivation layer is deposited. As mentioned hereinabove,the metal layer may be configured in a specific manner in accordancewith the embodiments set forth hereinabove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an integrated circuit constructed with bond padsaround a periphery thereof, in accordance with the prior art.

FIG. 2 illustrates a cross-sectional view of the integrated circuit ofFIG. 1 taken along line 2-2, showing underlying metal layers that areinterconnected by way of vias for facilitating electric communicationtherebetween.

FIG. 3 illustrates an integrated circuit constructed with bond pads overactive circuitry, in accordance with one embodiment.

FIG. 4 illustrates a cross-sectional view of the integrated circuit ofFIG. 3 taken along line 4-4, showing a plurality of vertically-spacedunderlying metal layers that are interconnected by way of vias forfacilitating electric communication therebetween.

FIG. 5 illustrates a method for fabricating a pad over active circuitsystem, in accordance with one embodiment.

FIGS. 6A-6E illustrate an integrated circuit during various stages ofprocessing in accordance with the method of FIG. 5, per one embodimentwhere the interconnect metal layer is meshed.

FIGS. 7A-7E illustrate an integrated circuit during various stages ofprocessing in accordance with the method of FIG. 5, per anotherembodiment where the interconnect metal layer is meshed.

FIGS. 8A-8E illustrate an integrated circuit during various stages ofprocessing in accordance with the method of FIG. 5, in accordance withanother embodiment where the interconnect metal layer takes on anenclosed “frame”-type configuration.

FIGS. 9A-9E illustrate an integrated circuit during various stages ofprocessing in accordance with the method of FIG. 5, per anotherembodiment where the interconnect metal layer takes on an enclosed“frame”-type configuration in addition to a meshed configuration.

FIG. 10 includes a graph showing the various area of the integratedcircuit that is saved by virtue of the previous embodiments.

FIG. 11 illustrates an exemplary system in which the integrated circuitof the various previous embodiments may be implemented.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 3 illustrates an integrated circuit 300 constructed with bond padsover active circuitry, in accordance with one embodiment. As shown, theintegrated circuit 300 is provided including a semiconductor platform301. Incorporated on the semiconductor platform 301 are acentrally-situated core 302 and a peripheral input/output (I/O) bus 304,which together define, at least in part, the “active circuit” of theintegrated circuit 300. In the context of the present description, theactive circuit 308 of the integrated circuit 300 may include the core302, I/O bus 304 and/or any device formed in the semiconductor platform301 of the integrated circuit 300.

As shown, a plurality of bond pads 306 is disposed, at least partially,above the active circuit 308 of the integrated circuit 300. Just by wayof example, the bond pads 306 may be disposed, at least partially, abovethe outer periphery of the I/O bus 304. Of course, however, the bondpads 306 may be disposed above the core 302, and/or any other part ofthe active circuit 308.

As can be seen, with respect to the prior art integrated circuit 100 ofFIG. 1, an area of the integrated circuit 300 is reduced, thus providinga more compact, cost effective integrated circuit.

FIG. 4 is a cross-sectional view of the integrated circuit 300 of FIG. 3taken along line 4-4. Similar to FIG. 3, the semiconductor platform 301is shown to include the centrally-situated core 302 and I/O bus 304,which together define the active circuit 308 of the integrated circuit300, at least in part.

FIG. 4 further illustrates a plurality of vertically-spaced underlyingmetal layers 406 that are interconnected by way of vias 408 forfacilitating electric communication therebetween. In one embodiment, thevarious vias described herein may be constructed with a tungstenmaterial or the like.

As further shown, the underlying metal layers 406 take on a stackedconfiguration for allowing various unillustrated interconnections withthe active circuit 308 of the integrated circuit 300. As an option, anunderlying dielectric layer 410 may be situated above active circuit308.

Deposited at least partially above the active circuit 308 of theintegrated circuit 300 (with the underlying dielectric layer 410optionally therebetween) is an interconnect metal layer 412. Suchinterconnect metal layer 412 is further electrically coupled to theunderlying metal layers 406 by way of additional vias 414. Aninter-metal dielectric (IMD) layer 416 is deposited, at least partially,above the interconnect metal layer 412. As an option, the inter-metaldielectric layer 146 may be constructed from a low-K dielectricmaterial, a fluorinated silica glass (FSG) material, or any other typeof desired material.

Defining the bond pads 306, is a top metal layer which is in electricalcommunication with the interconnect metal layer 412 by way ofinterconnect vias 420. As will soon be set forth, the interconnect vias420 may be configured in various ways.

As mentioned earlier, the bond pads 306 are positioned, at leastpartially, above the active circuit 308 of the integrated circuit 300 toreduce the required area of the semiconductor platform 301. To preventdamage to the active circuit 308 during the bonding process, theinterconnect metal layer 412 may be configured in a specific manner(i.e. the metal layer may be meshed, formed to define a frame forsupporting vias, etc.). More information regarding such meshed,frame-type configurations will be set forth hereinafter in greaterdetail.

FIG. 5 illustrates a method 500 for fabricating a pad over activecircuit system, in accordance with one embodiment. In one embodiment,the present method 500 may be carried out to produce an integratedcircuit such as those set forth in the remaining figures. Of course, itshould be noted that the present method 500 may be carried out in anydesired context.

Initially, in operation 502, an active circuit (i.e. see, for example,active circuit 308 and related components of FIGS. 3 and 4) isconstructed on a semiconductor platform, in accordance with conventionalprocedures and techniques.

Moreover, in operation 504, a metal layer is deposited, at leastpartially, above the active circuit. A plurality of interconnect vias505 are then formed. Next, in operation 506, a dielectric layer isdeposited, at least partially, above the interconnect metal layer.

A bond pad is subsequently formed in operation 508, at least partially,above the metal layer. Thereafter, a passivation layer is deposited inoperation 510. As an option, the passivation layer may be constructedfrom a SiON material or the like.

As mentioned hereinabove, the metal layer deposited in operation 504 maybe configured in accordance with the embodiments set forth herein (i.e.the metal layer may be meshed, formed to define a frame for supportingvias, etc.).

More information regarding the foregoing operations will now be setforth in the context of various exemplary embodiments. It should benoted that the following embodiments are set forth for illustrativepurposes only, and should not be construed as limiting in any manner.

FIGS. 6A-6E illustrate an integrated circuit 600 during various stagesof processing in accordance with the method 500 of FIG. 5, per oneembodiment where the interconnect metal layer is meshed. Of course, suchintegrated processing stages may be set forth in the context of anydesired process.

FIG. 6A illustrates a stage where an interconnect metal layer 604 isdeposited, in accordance with operation 504 of the method 500 of FIG. 5,for example. As illustrated, the interconnect metal layer 604 is meshedby including a plurality of openings 602 formed completely therethroughbetween an upper surface and a lower surface thereof. Of course, inanother embodiment, the openings may be formed only partiallytherethrough in the upper surface of the interconnect metal layer 604,without extending through the lower surface thereof.

Still yet, at least a portion of the openings 602 may be completelyenclosed around a periphery thereof. Also, the openings 602 may have asubstantially square configuration. Of course, any shape may be used perthe desires of the user.

Such openings 602 may be formed using standard photolithographytechniques such as etching, etc. In such embodiment, the openings 602may define a plurality of substantially linear first portions 603A and aplurality of substantially linear second portions 603B which intersect,to define a matrix of openings 602.

FIG. 6B illustrates a subsequent stage where a plurality interconnectvias 606 are formed in rows along a length of at least the firstportions, in accordance with operation 505 of the method 500 of FIG. 5,for example. The interconnect vias 606 serve to provide electriccommunication between the interconnect metal layer 604 and the bond pad,illustrated earlier.

In the present embodiment, the interconnect vias 606 may include atleast two spaced rows for each of the first portions 603B. Optionally, awidth of the first portions 603B may be enlarged to accommodate the twoor more spaced rows for each of the first portions 603B. As a furtheroption, the interconnect vias 606 may be equally spaced. Of course, theinterconnect vias 606 may take on any desired configuration.

Still yet, FIG. 6C illustrates still another processing stage where aninter-metal dielectric layer 610 is deposited, in accordance withoperation 506 of the method 500 of FIG. 5, for example.

FIG. 6D illustrates a subsequent processing stage where a top metallayer 612 is deposited above the inter-metal dielectric layer 610 inelectrical communication with the interconnect vias 606. Note, forexample, operation 508 of the method 500 of FIG. 5. Such top metal layer612 thus serves as the bond bad.

Finally, a passivation layer 614 is deposited, in accordance withoperation 510 of the method 500 of FIG. 5, for example. See FIG. 6E.

FIGS. 7A-7E illustrate an integrated circuit 700 during various stagesof processing in accordance with the method 500 of FIG. 5, per anotherembodiment where the interconnect metal layer is meshed. Of course, suchintegrated processing stages may be set forth in the context of anydesired process.

FIG. 7A illustrates a stage where an interconnect metal layer 704 isdeposited, in accordance with operation 504 of the method 500 of FIG. 5,for example. As illustrated, the interconnect metal layer 704 is meshedby including a plurality of openings 702 formed therein. As in theprevious embodiment, such openings 702 may define a plurality ofsubstantially linear first portions and a plurality of substantiallylinear second portions which intersect, to define a matrix of openings702.

In the present embodiment, the openings 702 may be larger in size withrespect to the previous embodiment of FIGS. 6A-6E. To this end, thelinear portions may be thinner, for reasons that will soon becomeapparent.

FIG. 7B illustrates a subsequent stage where a plurality interconnectvias 706 are formed in rows along a length of at least the firstportions, in accordance with operation 505 of the method 500 of FIG. 5,for example. The interconnect vias 706 serve to provide electriccommunication between the interconnect metal layer 704 and the bond pad,illustrated earlier.

As shown, the interconnect vias 706 may form only a single row on eachof the first portions. As is now apparent from the present and previousembodiment, the interconnect vias 706 may form any desired number ofrows and take on any desired configuration.

Still yet, FIG. 7C illustrates still another processing stage where aninter-metal dielectric layer 710 is deposited, in accordance withoperation 506 of the method 500 of FIG. 5, for example.

FIG. 7D illustrates a subsequent processing stage where a top metallayer 712 is deposited above the inter-metal dielectric layer 710 inelectrical communication with the interconnect vias 706. Note, forexample, operation 508 of the method 500 of FIG. 5. Finally, apassivation layer 714 is deposited, in accordance with operation 510 ofthe method 500 of FIG. 5, for example. See FIG. 7E.

FIGS. 8A-8E illustrate an integrated circuit 800 during various stagesof processing in accordance with the method 500 of FIG. 5, in accordancewith another embodiment where the interconnect metal layer takes on anenclosed “frame”-type configuration. Of course, such integratedprocessing stages may be set forth in the context of any desiredprocess.

FIG. 8A illustrates a stage where an interconnect metal layer 804 isdeposited, in accordance with operation 504 of the method 500 of FIG. 5,for example. As illustrated, the interconnect metal layer 804 defines aframe with an outer periphery and an inner periphery. Such frame mayoptionally be enclosed, as shown.

FIG. 8B illustrates a subsequent stage where a plurality interconnectvias 806 are formed along the frame, in accordance with operation 505 ofthe method 500 of FIG. 5, for example. The interconnect vias 806 serveto provide electric communication between the interconnect metal layer804 and the bond pad, illustrated earlier. As shown, the interconnectvias 806 may be formed along an entire length of the frame defined bythe interconnect metal layer 804.

FIG. 8C illustrates still another processing stage where an inter-metaldielectric layer 810 is deposited, in accordance with operation 506 ofthe method 500 of FIG. 5, for example.

FIG. 8D illustrates a subsequent processing stage where a top metallayer 812 is deposited above the inter-metal dielectric layer 810 inelectrical communication with the interconnect vias 806. Note, forexample, operation 508 of the method 500 of FIG. 5. Finally, apassivation layer 814 is deposited, in accordance with operation 510 ofthe method 500 of FIG. 5, for example. See FIG. 8E.

FIGS. 9A-9E illustrate an integrated circuit 900 during various stagesof processing in accordance with the method 500 of FIG. 5, per anotherembodiment where the interconnect metal layer takes on an enclosed“frame”-type configuration in addition to a meshed configuration. Ofcourse, such integrated processing stages may be set forth in thecontext of any desired process.

FIG. 9A illustrates a stage where an interconnect metal layer 904 isdeposited, in accordance with operation 504 of the method 500 of FIG. 5,for example. As illustrated, the interconnect metal layer 904 defines aframe with an outer periphery and an inner periphery. Such frame mayoptionally be enclosed, as shown.

The interconnect metal layer 904 may define an island 905 formed withinand spaced from the inner periphery of the frame of the interconnectmetal layer 904. Such island 905 of the interconnect metal layer 904 mayfurther include a plurality of openings 903 formed therein. Suchopenings 903 may be completely enclosed around a periphery thereof, andoptionally have a substantially square configuration.

FIG. 9B illustrates a subsequent stage where a plurality interconnectvias 906 are formed along the frame, in accordance with operation 505 ofthe method 500 of FIG. 5, for example. The interconnect vias 906 serveto provide electric communication between the interconnect metal layer904 and the bond pad, illustrated earlier. Similar to previousembodiments, the interconnect vias 906 may be formed along an entirelength of the frame defined by the interconnect metal layer 904.

FIG. 9C illustrates still another processing stage where an inter-metaldielectric layer 910 is deposited, in accordance with operation 506 ofthe method 500 of FIG. 5, for example.

FIG. 9D illustrates a subsequent processing stage where a top metallayer 912 is deposited above the inter-metal dielectric layer 910 inelectrical communication with the interconnect vias 906. Note, forexample, operation 508 of the method 500 of FIG. 5. Finally, apassivation layer 914 is deposited, in accordance with operation 510 ofthe method 500 of FIG. 5, for example. See FIG. 9E.

Thus, the interconnect metal layer of the aforementioned embodiments maybe adapted for not only preventing damage incurred during a bondingprocess, but also facilitating an interlock between the interconnectmetal layer and the inter-metal dielectric layer disposed between theinterconnect metal layer and the top metal layer. This is accomplishedby the dielectric material of the inter-metal dielectric layer beingdeposited within the frame, openings, etc. This thus strengthens theresultant integrated circuit.

FIG. 10 includes a graph 1000 showing the various area of the integratedcircuit that is saved by virtue of the previous embodiments. For asmaller integrated circuit where the pads are laid out in a staggered,triple tier, or quad tier configuration; an exemplary size-saving of theintegrated circuit is that shown in the figure.

For a core-limited integrated circuit, in order to maintain a small sizeand fit all necessary bond pads within the perimeter of the integratedcircuit, bond pad pitches are often reduced. There are traditionallyassembly limitations of bond pad pitch in production that meetacceptable assembly and test yields. For example, a production limit mayinclude a 45 micron pad pitch. Issues with such fine pitch devicessometimes require bonding very small bond pads, due to a smaller padopening. Thus, the wire diameter is usually reduced and this impacts thewire length which, in turn, creates a finer bond finger pitch on thesubstrate. To this end, the cost of the product is further increased.

By enabling the bonds to be placed over an active circuit without damageduring the bonding process, the limitation of compacting the pads is nolonger a hard requirement. The in-line pads can be spaced apart andstaggered, or placed in multiple rows/columns over a larger area abovethe active circuit.

It should be noted that the interconnection techniques discussed hereinmay be applicable to wire bonding, Au thermosonic stud bumping,flip-chip solder bump and tape automated bonding (TAB), etc.

FIG. 11 illustrates an exemplary computer system 1100 in which theintegrated circuit of the various previous embodiments may beimplemented. As shown, a computer system 1100 is provided including oneor more processors, such as processor 1101, which is connected to acommunication bus 1102. The computer system 1100 also includes a mainmemory 1104. Control logic (software) and data are stored in the mainmemory 1104 which may take the form of random access memory (RAM). Thecomputer system 1100 also includes a graphics module 1106 and a display1108, i.e. a computer monitor.

The computer system 1100 may also include a secondary storage 1110. Thesecondary storage 1110 includes, for example, a hard disk drive and/or aremovable storage drive, representing a floppy disk drive, a magnetictape drive, a compact disk drive, etc. The removable storage drive readsfrom and/or writes to a removable storage unit in a well known manner.Computer programs, or computer control logic algorithms, may be storedin the main memory 1104 and/or the secondary storage 1110. Such computerprograms, when executed, enable the computer system 1100 to performvarious functions. Memory 1104 and storage 1110 are thus examples ofcomputer-readable media.

In one embodiment, the integrated circuit of the various previousfigures may be implemented as the processor 1101 [i.e. a centralprocessing unit (CPU), etc.], the graphics module 1106, a chipset (i.e.a group of integrated circuits designed to work and sold as a unit forperforming related functions, etc.), or any other integrated circuit forthat matter. In the example of a graphics module 1106, such integratedcircuit may include a transform module, a lighting module, and arasterization module. Each of the foregoing modules may be situated on asingle semiconductor platform to form a graphics processing unit (GPU).

Still yet, the integrated circuit of the various previous figures may beimplemented in the context of a general computer system, a circuit boardsystem, a game console system dedicated for entertainment purposes, anapplication-specific system, or any other desired system.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

1. A system, comprising: a bus; a display in communication with the bus;a memory in communication with the bus; and an integrated circuit incommunication with the display and the memory via the bus, theintegrated circuit including an active circuit; a metal layer disposed,at least partially, above the active circuit; and a bond pad disposed,at least partially, above the metal layer; wherein the metal layer ismeshed.
 2. The system as recited in claim 1, wherein the system includesa general computer.
 3. The system as recited in claim 1, wherein thesystem includes a game console.
 4. The system as recited in claim 1,wherein the integrated circuit is selected from the group consisting ofa central processing unit, a graphics processing unit, and one of aplurality of integrated circuits included in a chipset.
 5. The system asrecited in claim 1, wherein the system includes a circuit board.